Tanning skin substances



" Patented Apr. 16, 1935 v I i A .uu-lrso STATES} i PATENT OFFICE NoDrawing. Application "August so, 1932, Serial No. 631,103

10 Claims. (01. 149-5) This invention relates to the tanning of skinsfate; say 36'parts, or I may use more, as for exand the like, and one ofits important objects is'to ample 48 or, say, 72 parts. Or I maysubstitute provide a tanning agent and process which will sodium sulfite(NazSOa) for the bisulfite, using, produce white leather. A furtherobject is to say, about 12.5 parts of the sulfite; I may also provide ataning agent and process which will substitute about 16v parts: sodiumthiosulfate 5 produce leather capable of being easily dyed, (NazSzOa)for the bisulfite. Another salt that especially by means of dyes whichform colored may be used is hydrosulflte (NazSzOQ. More lakes in or uponthe materiaL- To these and specifically I prefer the following: otherends the invention comprises the novel (a) 60 parts anhydrous sodium-bisulfate features hereinafter described. (NaHSOr), 16 parts titaniumoxide (TiOz), 10.4 10

In my improved tanning process I use a titaparts sodium .bisulfite(NaHSOa).

I nium salt, which isproduced by fusion of a mix- (b) 36 parts anhydrousbisulfate, 16 parts titure of titanium oxide and one or more alkalitanium oxide, 10.4 parts bisulfite. metal compounds of sulfur, as forexample sodium (0) 48 parts anhydrous bisulfate, '16 parts ti-'bisulfate and bisulfite. The titanium oxide used tanium oxide, 10.4parts bisulfite. 15 is preferably hydrated oxide which has not been (d)v 72 parts bisulfate, 16 parts titanium oxide, calcined, but in thespecific'examples of my in- 12.6 parts sodium sulflte (NazSOz).

, vention given below, the amount of the oxide is -(e) 72 partsbisulfate, 16 parts titaniumoxgiven on thedry or calcined basi, ide,15.8 parts anhydrous sodium thiosulfat 20 In one example of preparingthe titanium tan- (NazszOa) v 20 ning agent I convert titanium oxide(T102) into In example (e) the mixture'can be kept in the atitanium-sulfur compound, apparentlya sulfate fused state until sulfurceases tocome off (as the basicity of which can be varied by varyingdioxide, S02), but if desired the mass may be althe proportions of thereagents, by fusing therelowed to solidify before evolution of S02begins,

' with a sulfur compound of sodium or potassium. leaving in the productthe sulfur liberated in the Preferably I fuse with 16 parts titaniumoxide, 60 reaction. parts anhydrous sodium bisulfate (NaHSO4) and? 'Itis to be understood that the invention is not to the fusion I add about10.5 parts of sodium \limited to the details ,herein specificallystated, bisulflte (NaHSOs) and continue the fusion until asthese can bevaried without departure from I oxidation of the bisulfite is completed.The final its spirit. 30

product is mixed with water and is then used t I claim-- V v treat theskin substance, the latter being more or 1. In the art of tanning skinsubstances, fusless acid, preferably at a pH about 3.5. In this ing ananhydrous bisulfate of sodium or potasstep the concentration of theliquor is, by prefsium with titanium oxide,. fusing the product erence,such as will give it a titanium'content thereof with a bisulfite ofsodium or potassium, 5 (estimated as TiOz) of about 2 per cent of theand treating the-skin substance with the resultweight of the drainedskins. This treatment may ing product in water. I I require severalhours time, with agitation, after 2. In the artof tanning skinsubstances, treatwhich the pH of the liquor is brought to about 5.4 ingthe skin substance as in clainil, with the skin 46 by the addition of amild alkali, as-for example substance at a pH of about 3.5, and thenraising 4 borax, sodium carbonate or bicarbonate, prefer- :the pH valueof the liquor to about 5.4. ably the latter, followedby furtheragitation for a 3. The process set forth in-claim 1, in which shorttime. The result isa clear white leather the titanium concentration of'the liquor, estiwhich can be finished by any "well known p'romated astitanium oxide, is about 2- per cent of cedure such as 'is applicable tochrome-tanned the weight of the drained skin substance. 45

leather. The product of my process has the fur- 4. In the art oftanning'skin substances, fusing ther advantage that it can be readilydyed, the about 36 to about. 72 parts anhydrous sodium or titaniumcompound in the leather reacting with potassium bisulfatewith about 16parts titanium the dyestuff to form a lake the color of which deoxide,fusing the product thereof with sodium or 50 pends, of course, upon thedyestuif'employed. potassium bisulfite; and treating the skin sub- 50The proportions of the reagents employed in stance with the product ofthe usion.

preparing the tanning agent may vary consider- I 5. In the art oftanning ski substances, preably. For example, the amount of, the oxideand. paring a tanning agent by fusing with titanium bisulfite being thesame as in the example given oxide sodium or potassium bisulfate,and-fusing I may use less than 40 parts of the sodium bisultheproductwith sodium or potassium sulfite. 5 5

6. In the art of tanning skin substances, preparing a tanning agent byfusing with titanium oxide sodium or potassium anhydrous bisulfate inthe presence of sodium or potassium bisulfite.

7. In the art of tanning skin substances, preparing a tanning agent byfusing with titanium oxide sodium or potassium anhydrous bisulfate inthe presence of sodium or potassium thiosulfate'.

8. A tanning agent having the composition resulting from the fusion oftitanium oxide with sodium or potassium bisulfate in the presence of andin intimate contact with a sulfur compound of sodium or potassiumselected from the class composed of bisulnte, sulflte, thiosulfate, andhydrosulflte.

water, with the skin substance at a pH of substantially less than -'I.

10. A tanning agent having the composition resulting from the fusion oftitanium oxide with sodium or potassium, anhydrous bisulfate in thepresence of and in intimate contact with sodium or potassium hisulflte.

ADOLF SCHUBERT.

